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Incidence and Prevalence of Delirium Subtypes in an Adult ICU

A Systematic Review and Meta-Analysis*

Krewulak, Karla D., PhD1; Stelfox, Henry T., MD, PhD1–,4; Leigh, Jeanna Parsons, PhD1,2,4; Ely, E. Wesley, MD, MPH5,6; Fiest, Kirsten M., PhD1,3,4,7

doi: 10.1097/CCM.0000000000003402
Review Articles

Objectives: Use systematic review and meta-analytic methodology to estimate the pooled incidence, prevalence, and proportion of delirium cases for each delirium subtype (hypoactive, hyperactive, and mixed) in an adult ICU population.

Data Sources: We conducted a search of the MEDLINE, EMBASE, CINAHL, SCOPUS, Web of Science, and PsycINFO databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards from database inception until October 22, 2017, with no restrictions.

Study Selection: We included original research conducted in adults admitted to any medical, surgical, or speciality ICU that reported incidence or prevalence estimates of delirium according to delirium subtype.

Data Extraction: Data were extracted on sample size, population demographics, condition information, and reported delirium estimates.

Data Synthesis: Forty-eight studies (27,342 patients; 4,550 with delirium) with an overall pooled prevalence of 31% (95% CI, 24–41; I 2 = 99%) met inclusion criteria. The pooled incidence (n = 18 studies) of delirium subtypes were hyperactive (4% [95% CI, 2–6]; I 2 = 92%]), hypoactive (11% [95% CI, 8–17; I 2 = 97%]), and mixed (7% [95% CI, 4–11; I 2 = 97%]). The pooled prevalence (n = 31 studies) of delirium subtypes were hyperactive (4% [95% CI, 3–6; I 2 = 94%]), hypoactive (17% [95% CI, 13–22; I 2 = 97%]), and mixed (10% [95% CI, 6–16; I 2 = 99%]). The pooled prevalence of hypoactive delirium in study populations with a similarly high severity of illness or mechanically ventilated was higher (severity of illness: 29% [95% CI, 18–46%; I 2 = 95%], 100% mechanically ventilated: 35% [95% CI, 23–55%; I 2 = 93%]) compared with the pooled prevalence of hypoactive delirium.

Conclusions: Despite significant heterogeneity between studies, these data show the majority of delirious ICU patients to have hypoactive delirium, a finding with potential monitoring, management, and prognostic implications. The prevalence of hypoactive delirium varies between-study populations and is higher in patients with greater severity of illness.

1Department of Critical Care Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.

2Critical Care Strategic Clinical Network (CC SCN), Alberta Health Services, Calgary, AB, Canada.

3Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.

4O’Brien Institute for Public Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.

5Tennessee Valley Veteran’s Affairs Geriatric Research Education and Clinical Center (GRECC), Center for Health Services Research, Nashville, TN.

6Division of Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN.

7Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.

*See also p. 2058.

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Supported, in part, by the Critical Care Strategic Clinical Network.

Dr. Ely’s institution received funding from the National Institutes of Health (NIH) (AG027472, AG035117), Veteran's Affairs (VA) Merit, and the Tennessee Valley VA Geriatric Research Education and Clinical Center (GRECC); he received support for article research from the NIH; and he disclosed government work. The developer of the Confusion Assessment Method for the ICU (Dr. Ely) did not perform the evidence analysis and had no input into the outcome of this review. The remaining authors have disclosed that they do not have any potential conflicts of interest.

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